Chlorine exposure and the upper respiratory tract.

We read with great interest the report of SCHINS et al. [1] on their controlled human-exposure study of chlorine inhalation. The air pollutant studied, gaseous chlorine, is one of substantial relevance in terms of total industrial usage and involvement in emergency release scenarios. The authors referred to "…a paucity of human data on the effect of chlorine on the upper respiratory tract". Their literature review, however, overlooked two recent and pertinent studies from our institution pertaining to the effects of Cl 2 on both the upper and lower respiratory tracts. D9ALESSANDRO et al. [2] documented a significantly greater acute bronchial (obstructive) response in asthmatic versus normal volunteers exposed to 1.0, but not 0.4 parts per million (ppm) Cl 2 for 15 min [2]. SHUSTERMAN et al. [3] demonstrated significantly higher nasal irritation ratings and nasal congestion (assessed by rhino-manometry) among seasonal allergic rhinitic volunteers (as compared to normal controls) exposed to chlorine at 0.5 ppm615 min. A common denominator of these studies is the need to identify potentially susceptible subpopulations in order to provide the most sensitive assay for potential population-based health effects. The inability of SCHINS et al. [1] to document significant subjective complaints in response to Cl 2 exposures as high as 0.5 ppm66 h, may relate to the manner in which symptoms were recorded, which did not include baseline (pre-exposure) measures and was tempered by a physician9s subjective estimation of the likelihood of relatedness exposure. Moreover, the study did not employ objective physiological measures of nasal irritant response (e.g. rhinomano-metry, acoustic rhinometry, nasal peak flow measurement , or rhinostereometry). Given these limitations, the negative findings of the study should be viewed with caution, especially in light of other positive studies with comparable exposure levels that were not discussed. Nasal inflammatory and respiratory parameters in human volunteers during and after repeated exposure to chlorine. Blanc PD. Exaggerated responses to chlorine inhalation among persons with nonspecific airway hyper-reactivity. allergic rhinitis and non-rhinitic subjects react differentially to provocation with chlorine gas. We read with interest the comments of D. Shusterman and colleagues to our human exposure study with gaseous chlorine. Although it may seem like we have "overlooked" the two studies referred to in their letter, there are several reasons why these controlled human exposure studies were not discussed in our paper. The major reason is that we set out to study potential adverse effects of chlorine in a healthy …